Electrical conductor



(No Model.)

H. F. CAMPBELL. ELBGTRIGAL CONDUCTOR. 1No. 369,394. Patented Sept. 6,1887.

N. PETERS. PhnIn-Lilhogmphlr, Whhinllfln. 0.6.

UNITED STATES PATENT OFFICE.

HENRY F. CAMPBELL, OF CONCORD, NEW' HAMPSHIRE, ASSIGNOR TO THE CAMPBELLELECTRIC COMPANY, OF NEIV HAMPSHIRE.

ELECTRICAL CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 369,394, datedSeptember 6, 1887.

(No model.)

To aZZ whom it may concern:

Be it known that I, HENRY F. CAMP ELL, of Concord, county of Merrimac,State of New Hampshire, have invented an Improvement in ElectricalConductors, of which the following description, in connection with theaccompanying drawings, is a specification, like letters on the drawingsrepresenting like parts.

My invention relating to electric conductr0 ors has for its object toprevent disturbances arising from induction from neighboring wires orother disturbing influences.

Electric cables have been made in which each independent conductor,covered with the usual insulating material, is provided with an outermetallic covering, usually composed of a lead or copper tube, or of acovering of tinfoil, it having been supposed that such a COV. eringwould prevent the transmission of distll1'bl[lg currents to the wire.Experiment, however, has shown that such coverings are ineffectual, 'atleast for cutting ofl such currents as will produce disturbances in thetele phonic instruments of the present day.

I have discovered after long investigation that while an ordinarycovering composed of the metals usually employed for this purpose viz.,copper, lead, or tin, all good conductors of electricityareincfficient,there are certain 0 substances which, when employed as a covering orshield for an insulated wire,will greatly diminish or entirely annul thedisturbances referred to.

In another] application for Letters Patent,

3 5 No. 97,028, filed June 4,1883, I have described and claimed a shieldcomposed of paramagnetic and diamagnetic materials,it being many timesmore effectual than the coverings composed of diamagnetic material aloneheretoro fore employed. While the shield therein described is the bestknown to me for this purpose, there are other materials besides such acombination of paramagnetic and diamagnetic substances which can beemployed, and will 5 give far better results than the materials formerlyused.

All my investigations have shown that while the materials known andclassed as ,diamagnetic materials, including copper, lead, and

5c tin, which have been most commonly used on account of theirabundance, their electrical conductivity, andthe ease with which theymay be manipulated, are ineffectual. All the paramagnetic elements arefound to be effective in a very high degree; and the presentinventionconsists, mainly, in the combination, with an insulated conductor, of acovering or shield composed ol'one or more paramagnetic materials andwith means to connect the said shield in an electric circuit, wherebythe cur- 6 rent generated in the said shield may be conducted away fromit without passing to or affecting the conductor incloscd in the saidshield and protected thereby.

Figure 1 shows in transverse section a cable 5 5 composed of electricconductors embodying my invention, and Fig. 2 a longitudinal sectionthereof.

As herein shown, a series of independent conductors are united to form acable, the said conductors c, of any usual kind, being each intended toform .a portion of the circuit of telephonic or other electricalinstruments, and each being provided with a covering, 1), oiany usualand suitable insulating material, to prevent the currents from escapingfrom it.

Each insulated conductor a b is provided with an anti-inductive shieldor covering, 0, which in this instance is composed of paramagneticmaterial, either a single substance, such as iron, manganese, cobalt,nickel, or a composition of two or more of the said substances. Iron isconsidered the best paramagnetic when used alone, or as the chiefelement in quantity when two substances are used, as it stands at thehead of the list of materials classed as paramagnetics. The saidcovering 0 can be most conveniently made of a strip of iron annealed, orof a soft and flexible nature wound spirally upon the outside of the 0insulating material I), care being taken that each successive turn ofthe strip is in close contact with or partially overlaps the edge of theone already applied, so as to form a complete uninterrupted coverin Inorder to render the shields effective, to prevent the transmission ofelectric impulses from one to another of the wires incloscd therein, itis essential to provide means for dis sipating the currents generated inthe shields. ion This may be accomplished by making the said shields aportion of a complete circuit, as hereinafter described, and by certainpeculiar arrangements of the shielded conductors with relation to oneanother, which will form the subject of other applications for LettersPatent.

\Vhen the shields c of the different wires a are to form a part of acomplete electric circuit, they may be insulated from one another, or,if desired, may be in electrical contact with one another, as shown. Inthe former case each individual wire will be connected by a terminal, asdescribed in my former application referred to, with the ground or otherreturn circuit for conveying the currents away from the said shields,and thus preventing them from passing upon or affecting the wires a,inclosed within them.

\Vhen the shields are in contact with one another, as shown, theyconstitute practically a single conductor, and single terminals, t, of asimilar nature to those described in my former application, may beemployed at each end of the cable to connect the said shields with theground or with a metallic conductor, forming the return-circuit for thesaid shields, as described in another application for Letters Patent,filed August 20, 1883, and numbered 104,214.

I consider that the employment of an annealed strip or ribbon of steel,or of homogeneous iron or steel without fiber, or, in fact, any annealedor soft ribbon composed of iron as the base, is within my invention.

I am aware that awrought-iron pipe ortube has been used with aninsulated conductor to increase the tensile strength, and for purposesof defense against abrasion and the action of water, as shown in UnitedStates Patents Nos. 91,093 and 201,477.

I claim 1. An electric conductor having a covering of insulatingmaterial, combined with an antiinductive shield composed of paramagneticmaterial, substantially as described.

2. An electric conductor consisting of a con- I ducting-core, aninsulating covering therefor,

and an external shield of iron capable of ready magnetization anddemagnetization, as and for the purpose described.

In testimony whereof I have signed my name to this specification in thepresence of two sub scribing witnesses.

HENRY F. CAMPBELL.

W'itnesses:

Jos. P. LIvEnMoRn, W. H. SIGSTON.

